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Industrial Acetogenic Biocatalysts: A Comparative Metabolic and Genomic Analysis
Synthesis gas (syngas) fermentation by anaerobic acetogenic bacteria employing the Wood–Ljungdahl pathway is a bioprocess for production of biofuels and biocommodities. The major fermentation products of the most relevant biocatalytic strains (Clostridium ljungdahlii, C. autoethanogenum, C. ragsdale...
Autores principales: | , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Frontiers Media S.A.
2016
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4935695/ https://www.ncbi.nlm.nih.gov/pubmed/27458439 http://dx.doi.org/10.3389/fmicb.2016.01036 |
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author | Bengelsdorf, Frank R. Poehlein, Anja Linder, Sonja Erz, Catarina Hummel, Tim Hoffmeister, Sabrina Daniel, Rolf Dürre, Peter |
author_facet | Bengelsdorf, Frank R. Poehlein, Anja Linder, Sonja Erz, Catarina Hummel, Tim Hoffmeister, Sabrina Daniel, Rolf Dürre, Peter |
author_sort | Bengelsdorf, Frank R. |
collection | PubMed |
description | Synthesis gas (syngas) fermentation by anaerobic acetogenic bacteria employing the Wood–Ljungdahl pathway is a bioprocess for production of biofuels and biocommodities. The major fermentation products of the most relevant biocatalytic strains (Clostridium ljungdahlii, C. autoethanogenum, C. ragsdalei, and C. coskatii) are acetic acid and ethanol. A comparative metabolic and genomic analysis using the mentioned biocatalysts might offer targets for metabolic engineering and thus improve the production of compounds apart from ethanol. Autotrophic growth and product formation of the four wild type (WT) strains were compared in uncontrolled batch experiments. The genomes of C. ragsdalei and C. coskatii were sequenced and the genome sequences of all four biocatalytic strains analyzed in comparative manner. Growth and product spectra (acetate, ethanol, 2,3-butanediol) of C. autoethanogenum, C. ljungdahlii, and C. ragsdalei were rather similar. In contrast, C. coskatii produced significantly less ethanol and its genome sequence lacks two genes encoding aldehyde:ferredoxin oxidoreductases (AOR). Comparative genome sequence analysis of the four WT strains revealed high average nucleotide identity (ANI) of C. ljungdahlii and C. autoethanogenum (99.3%) and C. coskatii (98.3%). In contrast, C. ljungdahlii WT and C. ragsdalei WT showed an ANI-based similarity of only 95.8%. Additionally, recombinant C. ljungdahlii strains were constructed that harbor an artificial acetone synthesis operon (ASO) consisting of the following genes: adc, ctfA, ctfB, and thlA (encoding acetoacetate decarboxylase, acetoacetyl-CoA:acetate/butyrate:CoA-transferase subunits A and B, and thiolase) under the control of thlA promoter (P(thlA)) from C. acetobutylicum or native pta-ack promoter (P(pta-ack)) from C. ljungdahlii. Respective recombinant strains produced 2-propanol rather than acetone, due to the presence of a NADPH-dependent primary-secondary alcohol dehydrogenase that converts acetone to 2-propanol. Furthermore, the ClosTron(TM) system was used to construct an adhE1 integration mutant. These results provide extensive insights into genetic features of industrially relevant bacterial biocatalysts and expand the toolbox for metabolic engineering of acetogenic bacteria able to ferment syngas. |
format | Online Article Text |
id | pubmed-4935695 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2016 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-49356952016-07-25 Industrial Acetogenic Biocatalysts: A Comparative Metabolic and Genomic Analysis Bengelsdorf, Frank R. Poehlein, Anja Linder, Sonja Erz, Catarina Hummel, Tim Hoffmeister, Sabrina Daniel, Rolf Dürre, Peter Front Microbiol Microbiology Synthesis gas (syngas) fermentation by anaerobic acetogenic bacteria employing the Wood–Ljungdahl pathway is a bioprocess for production of biofuels and biocommodities. The major fermentation products of the most relevant biocatalytic strains (Clostridium ljungdahlii, C. autoethanogenum, C. ragsdalei, and C. coskatii) are acetic acid and ethanol. A comparative metabolic and genomic analysis using the mentioned biocatalysts might offer targets for metabolic engineering and thus improve the production of compounds apart from ethanol. Autotrophic growth and product formation of the four wild type (WT) strains were compared in uncontrolled batch experiments. The genomes of C. ragsdalei and C. coskatii were sequenced and the genome sequences of all four biocatalytic strains analyzed in comparative manner. Growth and product spectra (acetate, ethanol, 2,3-butanediol) of C. autoethanogenum, C. ljungdahlii, and C. ragsdalei were rather similar. In contrast, C. coskatii produced significantly less ethanol and its genome sequence lacks two genes encoding aldehyde:ferredoxin oxidoreductases (AOR). Comparative genome sequence analysis of the four WT strains revealed high average nucleotide identity (ANI) of C. ljungdahlii and C. autoethanogenum (99.3%) and C. coskatii (98.3%). In contrast, C. ljungdahlii WT and C. ragsdalei WT showed an ANI-based similarity of only 95.8%. Additionally, recombinant C. ljungdahlii strains were constructed that harbor an artificial acetone synthesis operon (ASO) consisting of the following genes: adc, ctfA, ctfB, and thlA (encoding acetoacetate decarboxylase, acetoacetyl-CoA:acetate/butyrate:CoA-transferase subunits A and B, and thiolase) under the control of thlA promoter (P(thlA)) from C. acetobutylicum or native pta-ack promoter (P(pta-ack)) from C. ljungdahlii. Respective recombinant strains produced 2-propanol rather than acetone, due to the presence of a NADPH-dependent primary-secondary alcohol dehydrogenase that converts acetone to 2-propanol. Furthermore, the ClosTron(TM) system was used to construct an adhE1 integration mutant. These results provide extensive insights into genetic features of industrially relevant bacterial biocatalysts and expand the toolbox for metabolic engineering of acetogenic bacteria able to ferment syngas. Frontiers Media S.A. 2016-07-07 /pmc/articles/PMC4935695/ /pubmed/27458439 http://dx.doi.org/10.3389/fmicb.2016.01036 Text en Copyright © 2016 Bengelsdorf, Poehlein, Linder, Erz, Hummel, Hoffmeister, Daniel and Dürre. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Microbiology Bengelsdorf, Frank R. Poehlein, Anja Linder, Sonja Erz, Catarina Hummel, Tim Hoffmeister, Sabrina Daniel, Rolf Dürre, Peter Industrial Acetogenic Biocatalysts: A Comparative Metabolic and Genomic Analysis |
title | Industrial Acetogenic Biocatalysts: A Comparative Metabolic and Genomic Analysis |
title_full | Industrial Acetogenic Biocatalysts: A Comparative Metabolic and Genomic Analysis |
title_fullStr | Industrial Acetogenic Biocatalysts: A Comparative Metabolic and Genomic Analysis |
title_full_unstemmed | Industrial Acetogenic Biocatalysts: A Comparative Metabolic and Genomic Analysis |
title_short | Industrial Acetogenic Biocatalysts: A Comparative Metabolic and Genomic Analysis |
title_sort | industrial acetogenic biocatalysts: a comparative metabolic and genomic analysis |
topic | Microbiology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4935695/ https://www.ncbi.nlm.nih.gov/pubmed/27458439 http://dx.doi.org/10.3389/fmicb.2016.01036 |
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